1. Field of the Invention
The present invention relates to an interactive floor planner apparatus, and particularly to an interactive floor planner apparatus having a ratsnest display function for use in designing arrangement and the like of a printed wiring board, a ceramic wiring board, or LSI functional blocks.
2. Description of the Related Art
Arrangement of parts to be packaged on a printed wiring board or a ceramic wiring board is designed with an interactive floor planner apparatus, as a CAD (Computer Aided Design) system. FIG. 13 is a diagram of a process of designing a printed wiring board. Circuitry of the printed wiring board is designed first. In designing the circuitry, an EDIF 2 in which parts realizing each functional block and information on logical connection between the parts are defined is created, and circuit operation is confirmed by simulation. In the logical connection information, a section where connection is required is defined as a group, and names of parts and pins required to be connected in the section are defined. Pin information, electrical specifications and the like of each of the parts are registered in a library 4.
For the packaging of parts on the wiring board, the board, part shape, land shape, line width, a number of layers, and other design specifications are defined in the library 4. On the basis of these pieces of data, a packaging design creating tool 6 creates a packaging design data file 8. The packaging design data file 8 refers to data required for the parts packaging design. In the packaging design process, editing, arrangement, wiring, checking and the like are performed with an interactive floor planner 10. Editing refers to the editing of signals, power supply, grounding lines, vias, lands, wide-area conductors, inhibited regions, marking and the like. Arrangement refers to arrangement of functional blocks on the board.
When the functional blocks are arranged, functional block information such as part names, arrangement coordinates, pin names, pin coordinates and the like of the functional blocks is written as part of the packaging design data file 8. Wiring refers to automatic or manual provision of wiring between pins of the functional blocks. Check refers to the checking of design rules such as line width, a line pitch and the like. On the basis of the packaging design data, a plan data file 14 is created with a general-purpose plan editing CAD system 12. In the meantime, the packaging design data file 8 is used to create NC data, mask data and the like, and the data is sent to a factory where the printed wiring board is fabricated.
In arranging a functional block in the arrangement process, connections between the functional block and another functional block are displayed as ratsnest for an optimum arrangement. The conventional interactive floor planner displays ratsnest in net units. Therefore, display of a plurality of nets becomes complicated, making it difficult to check connections between functional blocks. As in Japanese Patent Laid-Open No. Hei 8-137927, a system has been proposed which groups connecting relations between a plurality of parts by line type, line thickness, wiring color or the like and then displays the connecting relations, thereby making it possible for an operator to visually check the connecting relations between the plurality of parts easily and to thus reduce a design period.
However, the conventional interactive floor planner apparatus has the following problems. The method in Japanese Patent Laid-Open No. Hei 8-137927 groups only connecting relations between a plurality of parts and then displays the connecting relations; therefore, when a transmission functional block such as a resistance/buffer/switch or the like that is electrically passed through is connected between functional blocks, strength of connection between the functional blocks which connection is actually strong cannot be determined. In addition, in a case of a printed wiring board with a high density and a large number of functional blocks, grouping and displaying only connecting relations between parts makes it difficult to visually determine strength of the connections between the parts because of many display sections. Furthermore, in arranging functional blocks, for shorter net connection distance, the functional blocks need to be arranged with a direction of arrangement of the functional blocks in mind so as not to cause twists or the like. However, it is not possible to determine the direction of arrangement of the functional blocks with this display method, and it is consequently difficult to utilize the display method for consideration of the arrangement.
It is accordingly an object of the present invention to provide an interactive floor planner apparatus that makes it possible to visually determine strength of connection between parts.
In accordance with an aspect of the present invention, there is provided an interactive floor planner apparatus for determining a placement position of functional blocks, in which apparatus functional block information including information on pins and connection information on pin connection between the functional blocks are defined, the apparatus including: a functional block shape extracting unit for dividing each of the functional blocks into one or a plurality of parts on the basis of shape of the functional block obtained from the functional block information; an inter-functional block connection calculating unit for calculating a number of connections between pins belonging to parts of two functional blocks connected to each other, between the parts, as a number of connections between the parts on the basis of the connection information; and a ratsnest display unit for displaying the connections between the parts as a combined single line having a line width corresponding to the number of connections between the parts.
In accordance with another aspect of the present invention, there is provided an interactive floor planner apparatus wherein when connection between the parts of the two functional blocks is made via a transmission functional block having a predetermined function, the inter-functional block connection calculating unit calculates a number of connections between the parts connected via the transmission functional block, and the ratsnest display unit makes a display on the basis of the number of connections between the parts connected via the transmission block.
In accordance with a further aspect of the present invention, there is provided an interactive floor planner apparatus wherein the inter-functional block connection calculating unit calculates a number of connections between pins of the two functional blocks on the basis of the connection information, and when the two functional blocks are connected to each other via a transmission functional block having a predetermined function, the inter-functional block connection calculating unit calculates a number of connections between the functional blocks connected via the transmission functional block, and the ratsnest display unit displays the connection between the functional blocks on the basis of the number of connections between the functional blocks connected via the transmission block.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.